Vehicle Seat Frame Pipe Welding for Weight Reduction
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Solution Overview
Problem
Existing vehicle seat lifter mechanisms face challenges in achieving a balance between weight reduction and maintaining strength, particularly due to the need for increased wall thickness to enhance torsional and bending strength, which results in increased weight.
Innovation Solution
The design incorporates a pipe member with an outer diameter equal to that of the collar member, featuring a contact surface with a reduced outer diameter for secure welding, and a sloped surface contact to enhance weld strength, thereby increasing torsional and bending strength without increasing the pipe's wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the rear pipe has a smaller outer diameter than the collar, then the weight of the rear pipe is reduced, but the torsional strength of the welded spot and bending strength of the rear pipe are insufficient
Solution Approach 1:
The patent applies local quality by creating a contact surface portion with reduced outer diameter at the end portion of the rear pipe. This localized diameter reduction allows the pipe to maintain a smaller overall outer diameter (reducing weight) while providing a specific region with enhanced welding characteristics. The reduced diameter contact surface ensures adequate wall thickness at the welding location for sufficient torsional and bending strength without requiring the entire pipe to have large wall thickness.
2Strength
If the rear pipe has a large wall thickness, then the torsional strength and bending strength are sufficient, but the weight of the rear pipe increases
Solution Approach 1:
Instead of uniformly increasing wall thickness throughout the entire rear pipe, the patent applies local quality by concentrating the necessary structural strength at the critical welding location. The contact surface portion has reduced outer diameter which ensures adequate wall thickness specifically at the welding region for sufficient torsional and bending strength, while the rest of the pipe can have smaller wall thickness to reduce overall weight.
3Strength
If the outer diameter of the rear pipe is equal to the outer diameter of the collar, then the torsional strength is improved, but the wall thickness must be increased which increases weight
Solution Approach 1:
The patent resolves this contradiction by applying local quality through the contact surface portion design. The rear pipe has an outer diameter equal to the collar outer diameter at the contact surface portion, providing sufficient torsional strength where needed. However, this equal diameter is only maintained at the localized contact surface region, not throughout the entire pipe length, allowing the rest of the pipe to have reduced wall thickness and thus reduced overall weight.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a lightweight and high-strength lifter mechanism that effectively supports the seat cushion while minimizing the pipe's wall thickness, enhancing the overall structural integrity and reducing weight.
Implementation Method 1
The collar members are rotatably attached to the respective side frames
Implementation Method 2
The first member and the second member are secured to each other by welding, with the contact surface portion kept in contact with an inner peripheral portion of the second member
Data Source
AI summary
A vehicle seat frame includes a pair of side frames, a pair of cylindrical collar members, a pair of link members, and a pipe member coaxially secured at end portions to the collar members. At least one of the collar members is substantially equal in outer diameter to the pipe member. A contact surface portion having a reduced outer diameter is formed in an end portion of a first member, which is brought into contact with a second member. The first member is one of the pipe member and the collar member that is substantially equal in outer diameter to the pipe member, and the second member is the other one of them. The first member and the second member are secured to each other by welding, with the contact surface portion kept in contact with an inner peripheral portion of the second member.